Objective   To assess the correlation of pulmonary micropapillary adenocarcinoma with epidermal growth factor receptor (EGFR) and KRAS mutation status and determine their clinicopathological features.

  Methods   We divided 144 cases of lung adenocarcinoma into two groups according to the new diagnostic criteria for the classification of lung adenocarcinoma (published in 2011) : the micropapillary pattern (MPP) -positive group and the MPP-negative group, each with 77 cases.The MPP-positive group was further subdivided into three subgroups (+, ++, and +++) according to the proportion of the micropapillary component.EGFR and KRAS gene mutations were detected by real time PCR polymerase chain reaction.

  Results   Of the 144 cases of lung adenocarcinoma, 62 cases (43.1%) have EGFR gene mutation, whereas 9 cases (6.25%) have KRAS gene mutation.EGFR mutation is shown to be associated with gender (P=0.018) and tumor volume (P=0.016).EGFR mutation is significantly higher in the MPP-positive group than in the MPP-negative group (P < 0.001), whereas KRAS mutation is lower in MPP-positive group than in MPP-negative group (P=0.016).No significant difference in the frequency of EGFR mutation among the three MPP-positive subgroups was indicated (P=0.932).

  Conclusion   The frequency of EGFR mutation in MPPAC is higher compared with that in the other subtypes of lung adenocarcinoma.The frequency of KRAS mutation in MPPAC is lower compared with that in the other subtypes of lung adenocarcinoma.These results indicate its unique molecular biological characteristic.